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Synthesis and molecular structures of the magnesium and aluminum adducts of a niobium-oxo complex. X-ray crystal structures of [{NbOCl4(THF)}2Mg(THF)4] and [{NbOCl4(THF)}2AlCl(THF)3].
Autorzy
Rok wydania
1997
Czasopismo
Numer woluminu
36
Strony
2227-2229
DOI
10.1021/ic9610804
Kolekcja
Język
Angielski
Typ publikacji
Artykuł
The most active Ziegler−Natta catalysts of alkene polymerization are d0 metallocenes of the XIII, XIV, and XV groups. 1 On the other hand, vanadium catalysts 2 generally show a d2 or d3 configuration. However, d0 vanadium complexes have frequently been used as catalysts but were readily reduced to a lower oxidation state in the presence of a cocatalyst. The synthesis of high polymers based on simple Nb(V) species as catalysts has also been reported. 3 It could be expected that V(V) and Nb(V) complexes would be effective catalysts if they could be stabilized in their high oxidation state. 4 In this contribution, we describe the synthesis and characterization of Mg2+ and Al3+ niobium−oxo adducts. The chemistry of transition metal−oxo M=O (V, Nb, Ta) adducts with electropositive metal ions such as Mg2+ or Al3+ as components of the catalyst is unknown yet. In a previous paper we described the synthesis and properties of products formed during reaction between [MoOCl3(THF)2] and [MgCl2(THF)2]. 5 For a Mo/Mg 2:1 molar ratio in THF a crystalline salt [Mg(THF)6][MoOCl4(THF)]2 is formed which reacts further with 3 equiv of bis(tetrahydrofuran)magnesium dichloride yielding the ionic [Mg2(μ-Cl)3(THF)6][MoOCl4(THF)] compound. The [{MoOCl4(THF)}2Mg(THF)4] and [MgMo(μ-Cl)3Cl2O(THF)3] molecular compounds were readily obtained by interaction of [MoOCl3(THF)2] with [MgCl2(THF)2] in a 2:1 and 1:1 molar ratio in CH2Cl2, respectively. However, compounds [(ReMe4O)2Mg(THF)4] and [{o-C6H4(CH2)2WO}2Mg(THF)4] arise from Grignard reagents or MgR2 with R2O7 or WCl4O in THF. 6,7Similar adducts with Al3+ were unknown.
Słowa kluczowe
Adducts, Catalysts, Cations, Molecules, Tetrahydrofurans
Adres publiczny
https://doi.org/10.1021/ic9610804
Strona internetowa wydawcy
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